(1) Field of the Invention
The invention relates to a method of metallization in the fabrication of integrated circuits, and more particularly, to a method of metallization in which metal residue is decreased after metal etching in the manufacture of integrated circuits.
(2) Description of the Prior Art
In the manufacture of integrated circuit devices, multiple layers of metallization are often utilized.
FIG. 1 illustrates a portion of a partially completed integrated circuit device. Semiconductor device structures such as gate electrodes, not shown, may be formed in and on a semiconductor substrate 10. An insulating layer 12 is deposited over the device structures and planarized. A first metallization is performed to form metal lines 14. An intermetal dielectric layer 16 is deposited over the metal lines and filling the gaps between the lines as is conventional in the art. A second level of metallization is now to be formed.
Typically, a first barrier layer of titanium 18 is deposited over the intermetal dielectric 16. Then the metal layer 20 is deposited over the titanium layer. This metal layer 20 is typically an aluminum alloy such as AlSiCu. A capping titanium nitride layer 22 is then formed.
The metal layers 22, 20, and 18 are then etched to leave the desired metal line 24, shown in FIG. 2. However, after etching, metal residue 28 has been found on the surface of the intermetal dielectric layer 16, as shown in FIG. 2. These metal residues may cause shorting of the device. It is possible that the metal residue may be left because of silicon precipitates 26, shown in FIG. 1. It may be that these silicon precipitates are not etched away when the metal layers are etched, but themselves act as a mask so that metal residues 28 are left. These metal residues may comprise titanium from the titanium layer 18 or they may comprise aluminum or an aluminum alloy. It has been discovered that the transfer system in the metal deposition chamber can effect residue.
U.S. Pat. No. 5,658,828 to Lin et al teaches a method of forming an aluminum contact in which a first titanium layer is deposited at 0 to 375.degree. C., then an aluminum layer is deposited at 0 to 300.degree. C. Without breaking vacuum, another layer of aluminum is deposited at 400 to 550.degree. C. U.S. Pat. No. 4,716,050 to Green et al teaches a surface treatment at a temperature of less than 100.degree. C. to produce a surface layer comprising hydroxl groups before deposition of aluminum.